Open architecture tabletop patient support and coil system

ABSTRACT

A patient support structure for positioning a selected anatomy of interest for imaging in a magnetic resonance imaging scanner is disclosed. The structure includes a receptacle for receiving a removable tray that includes connectors for connecting local RF coils housed in the array to the MRI scanner, and connectors for positioning the local RF coils adjacent an area of interest to be imaged. A structure for elevating the patient support is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/989,898, filed Nov. 23, 2007, and U.S. Provisional Application No.60/989,904, filed Nov. 23, 2007, which are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention is directed to devices and methods for positioningRF coils adjacent an anatomy of interest for imaging, and forfacilitating connections between a magnetic imaging scanner and local RFcoils used for the imaging in the bore of the magnetic imaging scanner.

BACKGROUND

In magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR)signals given off by protons in the presence of a strong magnetic fieldare detected after excitation by a radio frequency (RF) signal usingantennae termed “RF coils”. Generally speaking, there are two types ofRF coils: whole body RF coils, which are used to image large segments ofa patient, and “local” or “surface” RF coils, which are configured toimage specific anatomies of interest, such as the knees, shoulders,neck, breasts, hands and head.

Whole body RF coils are typically provided with commercially availableMRI imaging systems. These RF coils provide a large field of view toaccommodate, for example, the chest and abdominal regions of a humansubject, and as a result, their fields couple to large amounts of tissueoutside the region of interest being imaged. Because of the large fieldof view, the signal to noise ratio (SNR) of the signal in the anatomy ofinterest is relatively high, and quality factor of the RF coil is low.

Local RF coils are reduced in size and designed to couple solely withtissue in the region of interest. Local RF coils, therefore, aretypically positioned as close as possible to the anatomy of interest,and limit the field of view of an MRI scan to the selected region. Theresult is a significantly improved SNR and quality factor, and a reducedimage size that provides higher resolution of the area of interest.

To provide high resolution images of selected anatomy at high SNR, it isincreasingly common to use a number of local RF coils simultaneously inparallel imaging techniques. In these techniques, images are acquiredfrom multiple receive channels, for example 8, 16 or 32 channelsreceiving signals from 8, 16 or 32 RF coils respectively. In a typicalmultiple coil array arrangement, for example, several adjacent coils areprovided for receiving signals during imaging. Coil switching,multiplexing, or dynamic coil selection strategies are used to optimizea subset of coils for imaging of anatomies of a smaller volume, or toswitch between areas of interest during the image acquisition or imagingprocedure.

To facilitate these parallel imaging techniques, there is a need for adevice that allows an operator to position various types of RF coilsadjacent an anatomy of interest while in the bore of a MRI scanner. Sucha device should further facilitate connections between the MRI scannerand the RF coils, and allow for circuitry to switch between the coils.The present invention addresses these issues.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides an assembly for magneticresonance imaging of a patient. The assembly comprises a patient supportstructure for positioning a local RF coil adjacent an anatomy ofinterest for imaging, and base removably coupled to the patient supportstructure for elevating the patient support structure, and a coilconnector for receiving the local RF coil. The base is configured forreceipt on a table sized and dimensioned for receipt in the bore of theMRI scanner, and the coil connector is coupled to an MR connectorconfigured for connection to the MRI scanner to receive signals from theMRI scanner for controlling local RF coil.

In another aspect, the patient support structure is configured forimaging of the breast, and includes an anterior ramp, a posterior ramp,and a first and a second arched structure extending laterally along theedges of the anterior ramp and the posterior ramp to define aninterventional opening therebetween.

In still another aspect, the base comprises a first platformcorresponding to the anterior ramp and a second platform correspondingto the posterior ramp. When the patient support structure is aligned onthe base, the portion of the ramp between the first platform and thesecond platform is aligned below and increases the interventionalopening.

In another aspect of the invention, at least one of the patient supportstructure and the base include a plurality of slots and the other of thepatient support structure and the base includes a correspondingplurality of tabs, wherein the patient support structure is selectivelycoupled to the base to minimize the possibility of tipping.

In still another aspect of the invention, the patient support structureincludes a receptacle for receiving a tray including the coil connector.The patient support structure can also include an integrated RF coil.The tray can include circuitry for switching between a first RF coilconnected to the connector in the tray and a second RF coil integratedin the patient support structure. The tray can also include the trayincludes a moveable cover for accessing one or more connectors.

In yet another aspect of the invention, the base includes a raised rimthat extends along the edges of the base between the first platform andthe second platform. The bottom surface of the base can also includealignment feature for aligning the base with a corresponding alignmentfeature in a table configured for receipt in an MRI scanner. Thealignment feature can, for example, be a tab or a slot.

The foregoing and other aspects of the invention will be described inthe detailed description which follows. In the description, reference ismade to the accompanying drawings which illustrate a preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a patient supported on a patient supportstructure constructed in accordance with the present invention.

FIG. 2 is a perspective view of the patient support as supported on abase.

FIG. 3 is an alternate perspective view of the patient support and baseconfiguration.

FIG. 4 is an exploded view illustrating the patient support, the base,and an underlying tabletop.

FIG. 5 is a bottom exploded view of the patient support structure 14 andassociated base 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures and more particularly to FIG. 1, a patientis shown as supported on a patient support structure 14. The patientsupport structure 14 is coupled to a base 16, on the MRI's patient table34 (FIG. 5). The patient can be moved into the bore of the MRI scanner10 for imaging.

Referring still to FIG. 2, the patient support structure 14 is the mainstructural component for supporting the patient and, as shown here,allows the patient to lie face down with the breasts hanging pendant,while positioned adjacent local RF coils for imaging. Specifically, thepatient support structure 14 consists of a head support area or anteriorsupport 9 and a lower support area or posterior support 7, with aninterventional opening 27 defined between, and positioned to receive thebreasts of the patient. Two arches 11 extend laterally along the opening27, connecting the head support 9 to the lower patient support 7,providing structure while maximizing the ability of medical personnel toaccess the breasts of a patient supported on the support member. Thearches 11 preferably have a cross section of less than three squareinches each. To increase the structural capacity of the patient support,a third cross member 96 (FIG. 4) may be incorporated. The third crossmember can be arched or straight and can be, for example, a thin,slender support adjacent to the patient's sternum, or a thin, slendersupport disposed along the patient's midline (left-right). When a thirdcross-member is used, it is preferably positioned as far anterior aspossible relative to the patient.

Referring still to FIG. 2, the patient support structure 14 furtherincludes a ramp 13 extending upward from the head support 9 and towardsthe interventional opening 27, and a ramp 15 extending from the opening27 toward the lower patient support 7. This configuration allowphysicians and technicians access to the breast from lateral, medial,superior, inferior and anterior approaches through the interventionalopening. The general construction of the patient support structure is 14described more fully in U.S. Pat. No. 7,379,769, issued on May 27, 2008,which is hereby incorporated by reference for its description of thisdevice. Additional aspects of this invention are also described in theco-pending patent applications Ser. No. 12/277,035 entitled“MICROCONTROLLER SYSTEM FOR IDENTIFYING RF COILS IN THE BORE OF AMAGNETIC RESONANCE IMAGING SYSTEM”, filed on even day herewith, which ishereby incorporated by reference.

Referring still to FIG. 2 and now also to FIG. 3. The patient supportstructure 14 including apertures 31 and 33 for receiving local RF coilsat locations selected to provide clinically relevant imaging,particularly to provide lateral imaging of the breast. In addition, RFcoils 29 a, 29 b, 29 c, 29 d can be integrated into the patient supportstructure 14 to allow imaging with a higher signal to noise ratio, andin regions outside of the breast. Relevant positions are adjacent to thegroin region (29 a), neck (29 b), underarm (29 c, 29 d) and adjacent tothe back. These RF coils can be either fixed or removable. In additionto the coils shown, other coils, such as chest wall coils for improvedimaging of the chest and auxiliary region, and interventional coils forimaging and providing interventional access points can also be used, aswell as scout coils for imaging regions associated with breast cancerincluding: coils located in armpit region for imaging local lymph nodes;coils located in neck region for imaging local lymph nodes; coilslocated in the groin region; and coils wrapping around the back forcoverage of the spine.

Referring still to FIGS. 2 and 3, and now also to FIG. 4, the base 16can be a removable structure that can be selectively coupled to thepatient support 14 to elevate the patient support 14, and to provideadditional support. Referring now specifically to FIG. 4, and also toFIG. 5, in one embodiment, the base structure 16 includes a plurality ofslots 64, 66, 68, and 70 that receive mating tabs 84, 86, and 88 formedin a bottom surface at the patient support structure 14 and mechanicallylink the patient support structure 14 and base 16. The base 16preferably includes platforms 20 and 22 at the front and back end, and anon-elevated portion 24 connecting the platforms 20 and 22. The elevatedplatforms 20 and 22 are preferably aligned with the anterior 9 area andposterior 7 portions of the patient support structure and enableadditional access to the breast by elevating the patient and patientsupport 14 (posterior direction) above the underlying tabletop therebyincreasing the size of the interventional opening 27 beneath thepatient. The non-elevated portion 24 advantageously incorporates araised rim 26 and 28 for entrapment of blood during biopsy procedures.

The removable base 16 further allows for the use of the same patientsupport structure 14 with various MRI systems 10. For example, a patientsupport structure 14 can be selectively positioned on a base 16 that isspecifically configured for a particular MRI system 10. The base 16,moreover, can be constructed at a height that is selected for aparticular bore diameter of an MRI scanner. For example, the patientsupport structure 14 could be placed on the MRI table 34 without thebase 16 when the MRI scanner has a 60 cm bore, but could be used incombination with the removable base 16 when the MRI scanner has a 70 cmbore, in order to provide better interventional access to the breasts,and to bring the breast tissues closer to the MRI's isocenter for betterimaging.

Referring now to FIG. 5, mirrors or prisms 41 and lighting elements 43to facilitate site lines to the breast for imaging or intervention canbe integrated into the base 16. An exemplary position for a mirror 41 islocated at the superior line of the breast. Alternatively, the mirror 41can be configured to be manually adjustable by the user. A low powerarray of lights can be powered, for example, through a connection to theMRI scanner 10 (not shown). Such lights illuminate the open region ofthe patient support 14, in order to aid in positioning the patient, coilarrays, and needles. RF coils, such as a loop coil 94 located centrallyon each breast, can also be integrated into the base 16. In thisapplication, a connector similar to the connector 17 described above canbe provided to allow connection either directly to the MRI scanner 10 orto the cable tray 60, described below. Connectors for connecting RFcoils and devices for coupling interventional devices such ascompression grids, or needle alignment devices can also be provided inthe base 16.

Although the base 16 is shown here as a separate component, the base 16can also be embodied by legs that retractably extend from a bottomsurface of the patient support 14 to raise or lower the patient support14. The configuration at the base 16 would be done by the operatorbefore the patient is positioned on the patient support 14, particularlyto adapt the patient support 14 to the diameter of the bore of the MRIscanner 10 being used, and to create optimal space for the breasts andfor physician access to the breasts.

Referring again to FIG. 5, the bottom surface of the base 16 can alsoinclude alignment features 40, 42, such as the tabs shown here, to alignthe base 16 with corresponding apertures 44, 46 in the table 34, and tomechanically couple the base 16 to the table 34 without the need fortools. The alignment features 40 and 42 can be used to guide the base 16into position on the table 34, and also to position the patient support14 correctly. Support structures in the base 16 that receive tabs 72, 74incorporated in the patient support 14 add rigidity to the patientsupport structure 14 and resist flex. Although a tab and slot connectionis shown here, it will be apparent that mechanical fastening devicessuch as clips, pegs, clamps or straps can be coupled to slots 44positioned along the edges of the table 34. As shown here, the bottomsurface of the patient support surface 14 preferably includes a similartab structure to allow direct connection of the patient supportstructure 14 to the table 34.

Referring still to FIGS. 2 though 5, both the patient support structure14 and the base 16 include a number of features which can aid inreducing the tendency of the patient support 14 to tip. Particularly,the base 16 is designed to be weight-bearing, and is configured to besubstantially as wide as the top surface of the patient supportstructure 14 extending as wide as possible in the left-right directionand to use substantially all of the cross-sectional area in the base.Therefore, when a patient is positioned on the patient support structure14, the patient does not overbalance the edge of the structure. Theload, moreover, is supported along the raised edges 30 and 32 of thetable 34 corresponding to the MRI system 10. As discussed above, thebase 16 includes slots 64, 66, 68, 70 (FIG. 4) for receiving matchingtabs 84, 86, 88 (FIG. 5) in the patient support structure 14. Inaddition to limiting the tendency to tip, these connectors ensurecentering of the patient support structure 14 upon entry to the MRIscanner 10. The corresponding slots and tabs, moreover, can provide anelectrical connection to power, for example, RF coil elements 94 (FIG.5) in the base 16.

Referring now to FIGS. 2 and 3, a receptacle 18 is provided in thepatient support structure 14 for receiving a cable tray 60, whichsimplifies connections between the local RF coils and the MRI scanner 10through the connector 62, as discussed below. Referring now also to FIG.5, the cable tray 60 is shown received in the cable tray receptacle 18of the patient support 14. The cable tray 60 provides an electricalconnection point for connecting local RF coils to the patient support,and is linked to connector 62 which is configured to be connected to thecontrol system of the MRI scanner 10 for driving the RF coils. To limitnoise, coaxial cables and signal lines are routed through the cable tray60 and to the MRI system 10. Local RF coils that are coupled to thepatient support structure 14 or to the base 16 can be routed orconnected to the cable tray 60 states indicator lights 80 a, 80 b, 80 c,can be provided to indicate that the RF coils connected to the cabletray 60 are a valid coil combination. An indicator 82 is activated bycircuitry in the cable tray 60 when the connector 62 is fully connectedto the MRI scanner 10.

The housing of the cable tray may, as shown, enclose the connectionpoints, and the electrical connections made by opening or removing apanel or panels 19 in the anterior end 9 of the patient support 14, sothat RF coils can be connected to receptacles in the cable tray 60. Inorder to facilitate access to the connections of the cable tray 60 bythe user, and to limit access by the patient, the panel 19 can be afolding, sliding or like covering that is integrated into the housing.Alternatively, the housing of the cable tray 60 can directly incorporateconnectors (plugs or receptacles) which permit electrically connectingdetachable RF coil arrays directly to the housing at cable tray 60. Thecable tray 60 is removably attached to the patient support 14 inreceptacle 18 to allow a user to interchange the cable tray 60 for asystem upgrade, transfer between magnets, or other reasons. Suitableconnectors include, for example, latches, sliders, hook and loopfasteners, threaded fasteners, quarter-turn fasteners, and othermechanical coupling devices.

Internally, the cable tray 60 can include RF circuits for signalfiltering, signal combination, shield current traps and baluns.Circuitry for determining the appropriate combination of RF coils canalso be provided, and may include, for example, a microprocessor, ormultiplexing or switching circuitry that provides intelligent selectionof the RF coil arrays for imaging. Visual indicators such as lightemitting diodes can be located in the cable tray 60 to provide coilstatus and configuration indicators to the user.

Although shown on a specific end of the patient support 14, the cabletray 60 can be mounted at the anterior support 9 or posterior support 7thereby allowing the cable tray 60 to be adapted to different MRIdevices or scanners 10. The cable tray 60 can be, as shown in thefigures, centered between the left and right sides of the patientsupport 14, and is preferably removable for cleaning. The cables arepreferably sized to be sufficiently long to allow left/right andanterior/posterior movement of an attached RF coil for breast imaging,and to take up slack and tension, but are restricted in length toprevent tangling or interference with the moving parts of the system, orinterference with relative motion between the patient support structure14 and the bore of the MRI scanner 10.

The cable tray 60 can include a plurality of plugs or receptaclescorresponding to cables attached to RF coil arrays and elements that aremoveable in the system. Cables can be permanently attached to the RFcoil, or can include a connector that mates with the coil element.Alternatively, cables can be permanently attached to the cable tray, andinclude connectors for receiving mating connectors associated with localRF coils and coil elements. The RF coils can, for example, be providedwith cords of 20-60 cm length which permit free positioning withoutundue signal loss or the possibility of looping.

Referring now to FIG. 5, a slider 50 coupled to the patient supportstructure 14 provides an attachment point for compression devices and RFcoils. The sliders 50 are rigidly attached to the patient supportstructure 14, and may be attached to the patient support structure 14 onthe posterior 9, anterior 7, or both sides of the interventional gap 27simultaneously. Compression plates and compression plates housing RFcoils can be coupled to the slider 50 with several degrees of freedomand can, for example, house coils specifically designed for improvedimaging of the chest wall. The RF coils in the compression system can becoupled to the MRI system 10 through the cable tray 60, as describedabove. Compression plates and other devices suitable for the applicationare described more fully in U.S. Pat. No. 7,379,769, issued on May 17,2008, which is hereby incorporated by reference for its description ofthese devices.

In use, therefore, the present invention provides many advantages overthe prior art, providing significantly improved access to breast tissuefor imaging and intervention, particularly from beneath the breast,superior and inferior to the breast. For newer MRI types havinggeometries with large bore sizes (for instance 70 cm versus 60 cm indiameter), the benefit of the larger bore can be utilized for breastimaging by raising the patient support structure 14 to a higher positionin the bore for greater access. Additionally, by removing the base 16,the patient support structure 14 can be lowered to provide room forlarger patients. The base 16, for example, can ensure access for thelarger magnet (i.e. 70 cm bore), while the patient support structure 14can be used without a base 16 for a smaller magnet (i.e. 60 cm bore),while the patient is located near the same relative central point in themagnet.

Integrated coils at openings located at the groin region can accommodatecoils allowing for survey scans of that region for signs of cancerprogression. RF coils may also be provided at the neck region, allowingscanning of the lymph nodes and spine in that region. RF coils may alsobe attached at the back region to allow for scanning of the spine whilethe patient is positioned prone for breast imaging. Through the use ofRF coil switching technology (i.e. the ability to sample from variouscombinations of coils in a dynamically switching fashion), these coilarrays can be selectively activated or deactivated during specificscanning protocols or dynamically through a protocol. i.e. scan thebreast region, then selectively scan the axilla then scan the back, etc.

An important feature of the disclosed invention is the ability toincorporate multiple coils to provide coverage for a selected anatomy,or regions of interest. These coils can be integrated into the frame ofthe tabletop, the base structure, or fixably attached to the tabletop byway of compression plates or support structures. The invention alsoimportantly provides structure for restraining a patient in anappropriate position for imaging throughout a procedure. The patientsupport structure 14 described above, for example, has been shown to besufficiently strong to support a patient of between three hundred andfifty and five hundred pounds with a safety factor of four, even withoutadditional supports or structures.

A preferred embodiment of the invention has been described inconsiderable detail. Many modifications and variations to the preferredembodiment described will be apparent to a person of ordinary skill inthe art. For example, although the invention is described herespecifically for use in breast imaging, it will be apparent to those ofskill in the art that many of the novel features described can beembodied in structures configured for other anatomies of interest.Although tab and slot connections have been described above in a numberof applications, it will be apparent that the slots and tabs can bereceived and that other types of mechanical connections can also beused. Furthermore, although the cable tray 60 and receptacle 18 areshown at a specific end of the patient support structure 14, it will beapparent to those of ordinary skill in the art that this orientationcould be received. Therefore, the invention should not be limited to theembodiment described. To apprise the public of the scope of thisinvention, the following claims are made:

1. An assembly for magnetic resonance imaging of a patient, the assemblycomprising: a patient support structure for positioning a local RF coiladjacent an anatomy of interest for imaging; a base removably coupled tothe patient support structure for elevating the patient supportstructure, the base being configured for receipt on a table sized anddimensioned for receipt in the bore of the MRI scanner; and a coilconnector for receiving the local RF coil, the coil connector beingcoupled to an MR connector configured for connection to an MR scanner toprovide signals from the MR scanner to the local RF coil.
 2. Theassembly as recited in claim 1, wherein the patient support structure isconfigured for imaging of the breast, and includes an anterior ramp, aposterior ramp, and a first and a second arched structure extendinglaterally along the edges of the anterior ramp and the posterior ramp todefine an interventional opening therebetween.
 3. The assembly asrecited in claim 2, wherein the base comprises a first platformcorresponding to the anterior ramp and a second platform correspondingto the posterior ramp, wherein when the patient support structure isaligned on the base, wherein the portion of the ramp between the firstplatform and the second platform is aligned below and increases theinterventional opening.
 4. The assembly as recited in claim 1 wherein atleast one of the patient support structure and the base include aplurality of slots and the other of the patient support structure andthe base includes a corresponding plurality of tabs, wherein the patientsupport structure is selectively coupled to the base.
 5. The assembly asrecited in claim 1, wherein the patient support structure includes areceptacle for receiving a tray including the coil connector.
 6. Theassembly as recited in claim 1, wherein the patient support structurefurther comprises an integrated RF coil.
 7. The assembly as recited inclaim 2, wherein a raised rim extends along the edges of the basebetween the first platform and the second platform.
 8. The assembly asrecited in claim 1, wherein the base comprises one or more legsremovably coupled to a bottom surface of the patient support structureto raise the patient support structure.
 9. The assembly as recited inclaim 1, wherein a bottom surface of the base comprises an alignmentfeature for aligning the base with a corresponding alignment feature ina table configured for receipt in an MRI scanner.
 10. The assembly asrecited in claim 9, wherein at least one of the alignment feature andthe corresponding alignment feature comprises a tab and the other of thealignment feature and the corresponding alignment feature comprises aslot.
 11. The assembly as recited in claim 5, wherein the tray comprisescircuitry for switching between a first RF coil connected to theconnector in the tray and a second RF coil integrated in the patientsupport structure.
 12. The assembly as recited in claim 5, wherein thetray includes a moveable cover for accessing one or more connectors. 13.The assembly as recited in claim 10, wherein the slot and tab are rigidand prevent tipping of the patient support structure and the base. 14.The assembly as recited in claim 1, wherein a width of the patientsupport structure and a width of the base are selected to extendsubstantially between the walls in the bore of the MRI scanner.
 15. Theassembly as recited in claim 10, wherein the slot and tab includeelectrical connectors for electrically connecting the patient supportstructure to the base.
 16. The assembly as recited in claim 2, furthercomprising at least one mirror coupled to the base to provide a sightline to the breast of the patient.
 17. The assembly as recited in claim1, further comprising at least one light coupled to the base toilluminate an anatomy of interest to be imaged.
 18. The assembly asrecited in claim 2, wherein the patient support structure comprises anintegrated RF coil for imaging at least one of a groin region, a neck,an underarm and a back of the patient.